Method for manufacturing semiconductor device

Background of the invention

1. Field of the invention

The present invention relates to a method for manufacturing a semiconductor device, and in particular, relates to a method for forming a pattern of a conductive layer, a semiconductor layer, or the like.

2. Description of the related art

Conventionally, a large number of thin films such as an insulating layer and a conductive layer are formed over a substrate and a lithography technique is appropriately used to manufacture a MOS transistor, a thin film transistor (hereinafter also referred to as a TFT), and a semiconductor device including such a transistor. A lithography technique is a technique in which a pattern of a circuit or the like called a photomask, which is formed using a light-blocking material over a transparent flat plate, is transferred to an aimed object by utilizing light. The lithography technique is widely used in a process of manufacturing a semiconductor integrated circuit and the like.

The manufacturing process using a lithography technique requires multiple steps such as resist application using a photosensitive resin called a photoresist, light exposure, development, etching using a resist as a mask, and resist removal. Therefore, the throughput is inevitably decreased as the number of lithography processes is increased.

For example, a technique for processing a pattern into a linear shape without using a photoresist is proposed in Patent Document 1 (Japanese Published Patent Application No. S63-84789). Patent Document 1 describes a technique in which a transparent conductive film (ITO) is linearly irradiated with an excimer laser beam to form a linear opening, so that a pattern is formed.

In addition, Patent Document 2 (Japanese Published Patent Application No. 2005-099500) describes a technique, in which a resist including aliphatic polyester is used; and the resist is selectively exposed to ultraviolet ray so that the resist in the ultraviolet-irradiated region is removed, thereby making a development step using a developing solution unnecessary and simplifying the lithography process.

Summary of the invention

An object of the present invention is to improve the throughput in a manufacturing process of a semiconductor device by reducing the number of lithography processes.

Another object of the present invention is to provide a pattern formation technique in a manufacturing process of a semiconductor device, which can also be applied to a large substrate.

One feature of the present invention is to form a mask for forming a pattern of a layer such as a semiconductor layer, a wiring layer, or an electrode layer, by utilizing laser ablation, instead of using a photoresist. A process for forming a pattern by utilizing laser ablation as in the present invention is also called a laser ablation patterning process (LAPP).

First, a light absorption layer and an insulating layer are stacked over a layer to be processed, and a mask formed from the insulating layer (or the insulating layer and the light absorption layer) is formed by laser beam irradiation through a photomask. By laser beam irradiation through a photomask, even a large area can be selectively irradiated at a time. Accordingly, it is possible to form a mask for processing a large area at a time.

When the insulating layer is stacked over the light absorption layer, a thick layer can be easily formed over the layer to be processed. By formation of the thick layer over the layer to be processed in this manner, damage to the layer to be processed due to laser beam irradiation can be prevented.

Next, by using the mask formed of the insulating layer (or the insulating layer and the light absorption layer) as an etching mask, the layer to be processed is etched, so that a layer having a desired pattern shape is formed.

The light absorption layer is formed using a material which absorbs a laser beam. The insulating layer is formed using a material which transmits a laser beam. In the light absorption layer and the insulating layer stacked over the layer to be processed, by laser beam irradiation from the insulating layer side, the laser beam is transmitted through the insulating layer and is absorbed by the light absorption layer. The light absorption layer is heated by energy of the absorbed laser beam, and at least the insulating layer stacked over the light absorption layer is (partially) broken and removed. A phenomenon in which an irradiated region is partially or entirely removed by energy of the laser beam as described above is called laser ablation. At this time, the light absorption layer may also be removed by the laser beam.

Laser beam irradiation is performed through a photomask. The photomask is formed of a region which transmits a laser beam and a region which blocks a laser beam, so that a desired pattern is formed. In the present invention, since laser beam irradiation is performed through the photomask, a laser beam transmitted through the light-transmitting region of the photomask is transmitted through the insulating layer and absorbed by the light absorption layer. Accordingly, in accordance with the formed pattern of the photomask, the insulating layer is subjected to laser ablation and removed. At this time, the light absorption layer may also be subjected to laser ablation and removed.

Next, the layer to be processed is etched using the left insulating layer (or the insulating layer and the light absorption layer) as a mask. The layer to be processed is left in accordance with the insulating layer (or the insulating layer and the light absorption layer) used as a mask. Accordingly, the layer to be processed is formed to have a pattern corresponding to the photomask. After the layer to be processed is processed into a desired shape, the insulating layer (or the insulating layer and the light absorption layer) used as a mask may be removed as needed.

The layer to be processed is formed using a conductive material or a semiconductor material. By utilizing laser ablation, a conductive layer or a semiconductor layer can be formed without using a lithography process using a photoresist.

One feature of the present invention is to include the steps of forming a layer to be processed; forming a light absorption layer over the layer to be processed; forming an insulating layer over the light absorption layer; irradiating the light absorption layer and the insulating layer with a laser beam through a photomask, so that at least an irradiated region of the insulating layer is removed; and etching the layer to be processed using a left part of the insulating layer as a mask.

Another feature of the present invention is to include the steps of forming a layer to be processed; forming a light absorption layer over the layer to be processed; forming an insulating layer over the light absorption layer; irradiating the light absorption layer and the insulating layer with a laser beam through a photomask, so that at least an irradiated region of the insulating layer is removed; and etching the layer to be processed using a left part of the light absorption layer as a mask, so that a layer having a tapered shape is formed.

Further, the layer having a tapered shape is formed by etching using a wet etching method or a combination of a dry etching method and a wet etching method.

Another feature of the present invention is to include the steps of forming a layer to be processed; forming a light absorption layer over the layer to be processed; forming an insulating layer over the light absorption layer; irradiating the light absorption layer and the insulating layer with a laser beam through a photomask, so that at least an irradiated region of the insulating layer is removed; and etching the layer to be processed using a left part of the insulating layer as a mask, so that a layer having a perpendicular shape is formed.

Further, the layer having a perpendicular shape is formed by etching using a dry etching method.

Another feature of the present invention is that the layer to be processed is formed using a conductive material or a semiconductor material.

Another feature of the present invention is that the light absorption layer is formed using a material which absorbs a laser beam.

Still another feature of the present invention is that the light absorption layer is formed using a conductive material, a semiconductor material, or an insulating material.

Further, another feature of the present invention is to form the light absorption layer using at least one of elements of chromium (Cr), molybdenum (Mo), nickel (Ni), titanium (Ti), cobalt (Co), copper (Cu), and aluminum (Al).

Further, another feature of the present invention is that the insulating layer is formed using a material which transmits a laser beam

Further, another feature of the present invention is that a photomask including a pattern formed of a region which transmits the laser beam and a region which blocks the laser beam is used.

In the present invention, a mask formed of an insulating layer or a stacked layer structure of an insulating layer and a light absorption layer can be manufactured by laser beam irradiation through a photomask. By using the mask, a semiconductor layer, a conductive layer, and the like can be processed into a desired shape.

By employing the present invention, lithography processes in manufacturing a semiconductor device can be reduced, and the throughput can be improved.

Brief description of the drawings

In the accompanying drawings:

FIGS. 1A to 1D are conceptual diagrams for explaining the present invention;

FIGS. 2A and 2B are conceptual diagrams for explaining the present invention;

FIGS. 3A to 3E are conceptual diagrams for explaining the present invention;

FIGS. 4A1 to 4D2 are conceptual diagrams for explaining the present invention;

FIG. 5 shows an example of a manufacturing method of a semiconductor device of the present invention;

FIGS. 6A to 6C show an example of a manufacturing method of a semiconductor device of the present invention;

FIGS. 7A to 7C show an example of a manufacturing method of a semiconductor device of the present invention;

FIGS. 8A to 8C show an example of a manufacturing method of a semiconductor device of the present invention;

FIGS. 9A and 9B show an example of a manufacturing method of a semiconductor device of the present invention;

FIGS. 10A and 10B are conceptual diagrams for explaining the present invention;

FIGS. 11A to 11C show an example of a manufacturing method of a display device of the present invention;

FIGS. 12A to 12C show an example of a manufacturing method of a display device of the present invention;

FIG. 13 shows a structure of a light emitting element which can be applied to the present invention;

FIGS. 14A to 14C show structures of a light emitting element which can be applied to the present invention;

FIGS. 15A to 15C show structures of a light emitting element which can be applied to the present invention;

FIG. 16 is a conceptual diagram for explaining the present invention;

FIGS. 17A to 17C are top views of display devices of the present invention;

FIGS. 18A and 18B are top views of display devices of the present invention;

FIGS. 19A and 19B show an example of a display device of the present invention;

FIGS. 20A to 20D are conceptual diagrams for explaining the present invention;

FIGS. 21A to 21C show an example of a manufacturing method of a semiconductor device of the present invention;

FIGS. 22A to 22D show an example of a manufacturing method of a semiconductor device of the present invention;

FIGS. 23A to 23C show an example of a manufacturing method of a semiconductor device of the present invention;

FIG. 24 shows an example of a display device of the present invention;

FIG. 25 shows an example of a display device of the present invention;

FIGS. 26A and 26B show an example of a display device of the present invention;

FIG. 27 shows an example of a display device of the present invention;

FIGS. 28A and 28B show structural examples of a display module of the present invention;

FIG. 29 shows an example of a display device of the present invention;

FIG. 30 is a block diagram showing a main configuration of an electronic device to which the present invention is applied;

FIG. 31 shows an example of a circuit configuration of a display device of the present invention;

FIG. 32 shows an example of a circuit configuration of a display device of the present invention;

FIG. 33 shows an example of a circuit configuration of a display device of the present invention;

FIGS. 34A and 34B show examples of electronic devices to which the present invention is applied;

FIGS. 35A to 35E show examples of electronic devices to which the present invention is applied;

FIG. 36 shows a structural example of a laser irradiation apparatus which can be applied to the present invention;

FIG. 37 shows an example of a display device of the present invention;

FIGS. 38A to 38C are conceptual diagrams for explaining the present invention; and

FIG. 39 shows an example of a display device of the present invention.

Description of the invention

Hereinafter, Embodiment Modes of the present invention will be described with reference to the accompanying drawings. It is to be noted that the present invention is not limited to the following description, and it is easily understood by those skilled in the art that modes and details thereof can be modified in various ways without departing from the spirit and scope of the present invention. Therefore, the present invention should not be interpreted as being limited to the following description of the embodiment modes. In the structures of the present invention which will be described below, the same portions or portions having similar functions are denoted by the same reference numerals in different drawings in some cases.

Embodiment Mode 1

One feature of the present invention is to form a layer such as a conductive layer or a semiconductor layer having a desired shape without using a lithography technique using a photoresist. A layer which is processed by using the present invention is also referred to as a layer to be processed. In this embodiment mode, a conductive layer such as a wiring layer, a gate electrode layer, a source electrode layer, or a drain electrode layer, or a semiconductor layer, which forms a transistor or the like for example, is processed.

One mode of a manufacturing method of a layer to be processed, to which the present invention is applied, will be described with reference to FIGS. 1A to 1D and FIGS. 2A and 2B.

First, a substrate 100, over which a layer to be processed 102, a light absorption layer 104, and an insulating layer 106 are sequentially stacked, is prepared. Then, the insulating layer 106 side of the substrate 100 is irradiated with a laser beam 114 through a photomask 108 (refer to FIG. 1A).

As the substrate 100, a glass substrate, a quartz substrate, a sapphire substrate, a ceramic substrate, a semiconductor substrate, or the like is used. A base insulating layer may be formed over the substrate 100. In that case, the base insulating layer is preferably formed using an insulating material such as silicon oxide (SiO.sub.x), silicon nitride (SiN.sub.x), silicon oxynitride (SiO.sub.xN.sub.y) (x>y), or silicon nitride oxide (SiN.sub.xO.sub.y) (x>y).

The layer to be processed 102 is formed of a material appropriate for its purpose. For example, when a conductive layer functioning as an electrode or a wiring is desired to be formed as the layer to be processed 102, the layer to be processed 102 is formed using a conductive material. As the conductive material, an element such as silver (Ag), gold (Au), nickel (Ni), platinum (Pt), palladium (Pd), iridium (Ir), rhodium (Rh), tantalum (Ta), tungsten (W), titanium (Ti), molybdenum (Mo), aluminum (Al), or copper (Cu), or an alloy material or a compound material containing the element as its main component can be used. The layer to be processed 102 can be formed by a sputtering method, a CVD method, or the like using the conductive material with a single layer structure or a stacked layer structure.

When a semiconductor layer forming a channel or the like is desired to be formed as the layer to be processed 102, the layer to be processed 102 is formed using a semiconductor material. As the semiconductor material, silicon, silicon germanium, or the like can be used. Further, as the layer to be processed 102, an amorphous semiconductor layer may be formed, or a crystalline semiconductor layer may be formed. The layer to be processed 102 can be formed by a sputtering method, a CVD method, or the like using the semiconductor material with a single layer structure or a stacked layer structure.

The light absorption layer 104 is formed of a material which can absorb a laser beam. Further, it is preferable to use a material having a boiling point or a sublimation point lower than a melting point of the layer to be processed 102, which is placed below the light absorption layer 104, for the light absorption layer 104. For example, the light absorption layer 104 can be formed using a conductive material, a semiconductor material, or an insulating material. Specifically, a conductive material such as any element of chromium (Cr), molybdenum (Mo), nickel (Ni), titanium (Ti), cobalt (Co), copper (Cu), and aluminum (Al); or an alloy material or a compound containing the element as its main component can be used. As the compound containing the element as its main component, a nitrogen compound, an oxygen compound, a carbon compound, a halogen compound, or the like can be used, and for example, aluminum nitride, tungsten nitride, tantalum nitride, or the like can be used. Alternatively, a semiconductor material such as silicon, germanium, silicon germanium, molybdenum oxide, tin oxide, bismuth oxide, vanadium oxide, nickel oxide, zinc oxide, gallium arsenide, gallium nitride, indium oxide, indium phosphide, indium nitride, cadmium sulfide, cadmium telluride, or strontium titanate can be used. Further alternatively, an organic resin material such as polyimide, acrylic, polyamide, polyimideamide, resist, or benzocyclobutene; or an insulating material such as siloxane or polysilazane can be used. Further, zinc sulfide, silicon nitride, mercury sulfide, aluminum chloride, or the like can be used. The light absorption layer 104 can be formed by an evaporation method, a sputtering method, a CVD method, or the like using the above-described material with a single layer structure or a stacked layer structure. In the case where the light absorption layer 104 is formed using the insulating material, it can be formed by a coating method. Further, hydrogen or an inert gas (rare gas such as helium (He), argon (Ar), krypton (Kr), neon (Ne), or xenon (Xe)) can be added to the light absorption layer 104. When hydrogen or an inert gas is added to the light absorption layer 104, discharge of a gas from the light absorption layer 104 or evaporation of the light absorption layer 104 can be easily caused in subsequent laser beam irradiation.

The insulating layer 106 is formed using a material which can transmit a laser beam. For example, a light-transmitting inorganic insulating material or organic insulating material, or the like can be used. As the inorganic insulating material, silicon oxide, silicon nitride, silicon oxynitride, silicon nitride oxide, or the like can be used. As the organic insulating material, an organic resin such as polyimide, acrylic, polyamide, polyimide amide, benzocyclobutene, or an epoxy resin can be used. The insulating layer 106 can be formed by a sputtering method, a CVD method, a coating method, or the like using the above material with a single layer structure or a stacked layer structure.

The photomask 108 includes a region which transmits a laser beam (hereinafter also referred to as a light-transmitting region) 110 and a region which blocks a laser beam (hereinafter also referred to as a light-blocking region) 112, and the light-transmitting region 110 and the light-blocking region 112 form a desired pattern. For example, in the photomask 108, a desired pattern is formed using a light-blocking material on a surface of a light-transmitting substrate. It is to be noted that a material for forming the light-blocking region 112 needs to be favorable in light-blocking property and resistant to energy of the laser beam 114. For example, in the case of using an excimer laser beam for the laser beam 114, tungsten, molybdenum, or aluminum can be used.

For the laser beam 114, a laser beam having such energy that can be absorbed by the light absorption layer 104 is appropriately selected. Typically, a laser beam of an ultraviolet region, a visible region, or an infrared region can be appropriately selected for irradiation.

As a laser oscillator which can produce such laser beams, the following can be used: an excimer laser such as a KrF, ArF, or XeCl laser; a gas laser such as a He, He--Cd, Ar, He--Ne, or HF laser; a solid-state laser using, as a medium, single crystalline YAG, YVO.sub.4, forsterite (Mg.sub.2SiO.sub.4), YAlO.sub.3, or GdVO.sub.4, or polycrystalline (ceramic) YAG, Y.sub.2O.sub.3, YVO.sub.4, YAlO.sub.3, or GdVO.sub.4, which is doped with one or more of Nd, Yb, Cr, Ti, Ho, Er, Tm, and Ta as a dopant; or a semiconductor laser such as a GaN, GaAs, GaAlAs, or InGaAsP laser. It is to be noted that in the case of using a solid-state laser, it is preferable to use a laser beam having a wave that is appropriately selected from the fundamental wave to the fifth harmonic.

For the laser beam 114, a continuous wave laser beam or a pulsed laser beam can appropriately be used. For the pulsed laser beam, a repetition rate of several tens of Hz to several KHz is usually used. Alternatively, a pulsed laser, which can emit a laser beam at a repetition rate of 10 MHz or more, that is much higher than the usual, and with a pulse width in the range of picoseconds or in the range of femtoseconds (10.sup.-15 seconds), may be used.

A cross-sectional shape of the laser beam 114 may be a circular shape, an elliptic shape, a rectangular shape, or a linear shape (in a strict sense, a narrow rectangular shape) as appropriate. The laser beam 114 is preferably shaped to have such a cross-sectional shape by an optical system.

Energy of the laser beam 114 preferably has such a level that can cause a gas in the light absorption layer 104 to be discharged or the light absorption layer 104 to be evaporated.

In FIG. 1A, the laser beam 114 is transmitted through the light-transmitting region 110 of the photomask 108 to reach the surface of the insulating layer 106.

Further, the laser beam 114 is transmitted through the insulating layer 106 and absorbed by the light absorption layer 104. A region which the laser beam 114 reaches (hereinafter also referred to as an irradiated region) of the light absorption layer 104 is subjected to laser ablation, and the light absorption layer 104 as well as the insulating layer 106 stacked thereover is partially removed (refer to FIG. 1B). A left portion of the light absorption layer 104 is separated into light absorption layers 116a, 116b, 116c, and 116d. At the same time, the insulating layer 106 is separated into insulating layers 118a, 118b, 118c, and 118d. The left light absorption layers 116a to 116d and insulating layers 118a to 118d function as etching masks in etching the layer to be processed 102. It is to be noted that a pattern of the left light absorption layers 116a to 116d and insulating layers 118a to 118d corresponds to the pattern formed in the photomask 108, specifically the pattern formed of the light-blocking region 112.

In the laser ablation caused here, the irradiated region of the light absorption layer 104 is evaporated, and the irradiated region of the light absorption layer 104 and a part of the insulating layer 106 over the irradiated region are removed (or scattered) by energy of the laser beam 114 absorbed by the light absorption layer 104.

Since the etching masks are formed by utilizing laser ablation in the above-described manner, a step for applying a resist and a development step using a developing solution in a lithography process using a photoresist can be omitted. Accordingly, loss of materials such as a photoresist material and a developing solution can be prevented. Further, since the substrate does not need to be rotated, the present invention can more easily be applied to a large substrate. Further, since laser beam irradiation is performed through a photomask, even a large area can be selectively irradiated at a time. Accordingly, it is possible to form a mask pattern in a large area at a time.

Further, in the present invention, a layer functioning as a mask has a stacked layer structure of the light absorption layer and the insulating layer. By formation of the insulating layer over the light absorption layer in this manner, the mask can be easily thickened. Therefore, in laser beam irradiation, damage to the layer to be processed formed below the mask can be prevented.

In a usual lithography process, a mask pattern for etching a layer to be processed is formed through steps such as resist coating, light exposure, development, etching, and removal of the resist, with an exposure apparatus including a complex optical system such as a stepper. On the other hand, in the present invention, since a mask pattern is formed by utilizing laser ablation, an apparatus for resist coating, development, removal of the resist, and the like is not needed. By applying the present invention, maintenance of an apparatus for forming a pattern can be facilitated.

After irradiation with the laser beam 114, a gas such as N.sub.2 or air may be jetted to the side of the substrate 100, which is irradiated with the laser beam 114. Alternatively, the substrate 100 may be washed with a liquid that is a non-reactant such as water. Thus, by jetting a gas or washing with a liquid, dusts, residues, and the like due to ablation can be reduced.

Next, by using the left light absorption layers 116a to 116d and insulating layers 118a to 118b as masks, the layer to be processed 102 is etched to form layers to be processed 120a, 120b, 120c, and 120d (refer to FIG. 1C). The layers to be processed 120a to 120d each have a desired pattern shape, and a conductive layer functioning as a wiring, an electrode, or the like or a semiconductor layer is formed. The pattern shape of the layers to be processed 120a to 120d corresponds to the pattern formed in the photomask 108. Specifically, the pattern shape of the layers to be processed 120a to 120d corresponds to the pattern of the light-blocking region 112 formed in the photomask 108. The left light-absorption layers 116a to 116d and insulating layers 118a to 118d function as etching masks.

The layer to be processed 102 is subjected to anisotropic etching or isotropic etching, so that the layers to be processed 120a to 120d are formed. Etching may be performed by a dry etching method, a wet etching method, or a combination of a dry etching method and a wet etching method.

In general, when a wet etching method is used, an object to be etched (in this embodiment mode, the layers to be processed 120a to 120d) has an isotropic shape. Therefore, a wet etching method is employed for the isotropic etching. On the other hand, a dry etching method has a chemical etching aspect in which etching is performed by a chemical reaction and a physical etching aspect in which etching is performed physically by a sputtering effect or the like. The chemical etching is isotropic, the physical etching is anisotropic, and the ratio of both the etchings is changed depending on the structure of an apparatus or the like. Since both anisotropic etching and isotropic etching can be performed depending on the ratio of the chemical etching aspect and the physical etching aspect when using a dry etching method, a dry etching method can be applied to both etchings.

When using a dry etching method, a gas, by which a selection ratio of the etching rate of the layer to be processed 102 to the etching rate of the insulating layers 118a to 118d and the light absorption layers 116a to 116d is high, is used as an etching gas. For example, a fluorine-based gas or a chlorine-based gas such as CF.sub.4, CHF.sub.3, NF.sub.3, Cl.sub.2, or BCl.sub.3 can be employed. An inert gas such as He or argon or an O.sub.2 gas may be appropriately added to the etching gas. For example, in the case where the layer to be processed 102 is formed of tungsten, the light absorption layers 116a to 116d are formed of chromium, and the insulating layers 118a to 118d are formed of silicon oxynitride, a mixed gas of CF.sub.4, Cl.sub.2, and O.sub.2 is used as an etching gas.

In the case where a dry etching method is used, an uppermost layer portion, which is upper layer portions of the insulating layers 118a to 118d here, may also be etched, so that the film thicknesses thereof are reduced (referred to as film-reduction).

In the case where a wet etching method is used, a solution, by which a selection ratio of the etching rate of the layer to be processed 102 to the etching rate of the insulating layers 118a to 118d and the light absorption layers 116a to 116d can be obtained, is used as an etchant. For example, an acidic solution of hydrofluoric acid, phosphoric acid, nitric acid, acetic acid, sulfuric acid, or the like or an alkaline solution of potassium hydroxide, hydrazine, ethylenediamine, or the like can be used. Further, pure water or a buffering agent may be appropriately added to the etchant. For example, in the case where the layer to be processed 102 is formed of molybdenum, the light absorption layer 104 is formed of chromium, and the insulating layer 106 is formed of silicon oxynitride, an acid in which phosphoric acid, acetic acid, nitric acid, and pure water are mixed at a ratio of 85:5:5:5 by vol % (in this specification, also referred to as an aluminum mixed acid solution) can be used as an etchant. Further, in the case where the layer to be processed 102 is formed using tungsten, a solution in which a 28 wt % ammonia solution, a 31 wt % hydrogen peroxide solution, and pure water are mixed at a ratio of 3:5:2 by vol % (in this specification, hereinafter also referred to as an ammonia hydrogen peroxide mixture) can be used. For example, the etching rate of tungsten (W) is about 24 nm/min in the ammonia hydrogen peroxide mixture. Further, the etching rate of tungsten nitride is about 250 nm/min in the ammonia hydrogen peroxide mixture.

FIG. 1C shows an example in which part of the layer to be processed 102 is removed by anisotropic etching, so that the layers to be processed 120a to 120d are formed. Side surfaces (sidewalls) of the layers to be processed 120a to 120d, which are etched by anisotropic etching, each have a perpendicular shape.

FIG. 2A shows an example in which part of the layer to be processed 102 is removed by isotropic etching, so that layers to be processed 220a, 220b, 220c, and 220d are formed. The process up to the step for forming the light absorption layers 116a to 116d and the insulating layers 118a to 118d to serve as etching masks is the same as that of FIG. 1B. Side surfaces (sidewalls) of the layers to be processed 220a to 220d, which are etched by isotropic etching, each have a tapered shape.

In the present invention, the layer functioning as the etching mask has a stacked layer structure of the light absorption layer and the insulating layer; therefore, a selection ratio of the etching rate of a layer to be etched to the etching rate of the mask can be easily high. In addition, since the mask can be thick by forming the insulating layer over the light absorption layer, a film-reduction in dry etching does not have a level to arise a big problem.

In forming a mask from an insulating layer and a light absorption layer by laser ablation, an influence to a layer to be processed, which exists in a lower layer, is a concern. However, since the layer to be processed placed below an irradiated region with a laser beam is removed at the time of etching, there are no particular problems.

Next, the light absorption layers 116a to 116d and the insulating layers 118a to 118d are removed (refer to FIG. 1D and FIG. 2B). The light absorption layers 116a to 116d and the insulating layers 118a to 118d may be removed by appropriately selecting: a method for etching the layers by etching utilizing a dry etching method or a wet etching method, or a method for removing the layers by laser ablation through laser beam irradiation. Further, when the light absorption layers 116a to 116d and the insulating layers 118a to 118d are removed by laser ablation, jetting of a gas such as N.sub.2 or air or washing with a liquid may be performed from the laser beam irradiation side. In the above-described manner, the layers to be processed 120a to 120d having a desired pattern shape can be obtained.

Further, by employing the present invention, a conductive layer formed over a wiring substrate or a conductive layer functioning as an antenna used for an RF tag or the like can be formed as well.

By employing the present invention, a layer having a desired pattern shape can be formed without using a lithography process using a photoresist. Accordingly, a lithography process can be simplified, and the throughput can be improved.

Further, with the use of a linear laser beam or a planar laser beam having a large area such as a rectangular laser beam or a circular laser beam, a plurality of regions can be irradiated with a laser beam in a short time. Accordingly, by employing the present invention to a large substrate, a lot of patterns can be formed in a short time, whereby mass productivity can be improved.

Embodiment Mode 2

In this embodiment mode, a method for manufacturing a plurality of conductive layers, which function as gate electrode layers or wiring layers, using the present invention, will be described with reference to FIGS. 4A1 to 4D2.

First, a substrate 400, over which a conductive layer 402, a light absorption layer 404, and an insulating layer 406 are sequentially stacked, is prepared. Then, the insulating layer 406 side of the substrate 400 is irradiated with a laser beam 414 through a photomask 408 (refer to FIG. 4A1).

The substrate 400 may be a glass substrate, a quartz substrate, a sapphire substrate, a ceramic substrate, a semiconductor substrate, or the like. Over the substrate 400, a base insulating layer may be formed using an insulating material such as silicon oxide, silicon nitride, silicon oxynitride, or silicon nitride oxide.

The conductive layer 402 is formed of a conductive material such as an element, e.g. silver (Ag), gold (Au), nickel (Ni), platinum (Pt), palladium (Pd), iridium (Ir), rhodium (Rh), tantalum (Ta), tungsten (W), titanium (Ti), molybdenum (Mo), aluminum (Al), or copper (Cu) or an alloy material or a compound material containing the element as its main component. Further, the conductive layer 402 may have a single layer structure or a stacked layer structure. For example, a single layer structure using a tungsten layer; a two-layer structure in which a tantalum nitride layer and a tungsten layer are stacked or a tungsten nitride layer and a molybdenum layer are stacked; a three-layer structure in which a molybdenum layer, an aluminum layer, and a molybdenum layer are stacked; or the like can be formed.

The conductive layer 402 is formed by a sputtering method, a physical vapor deposition (PVD) method, a chemical vapor deposition (CVD) method such as a low pressure CVD (LPCVD) method or a plasma CVD method, or the like.

The light absorption layer 404 is formed by using a material which can absorb the laser beam 414. For the light absorption layer 404, it is preferable to use a material having a boiling point or a sublimation point lower than a melting point of the conductive layer 402, which is placed below the light absorption layer 404. For example, the light absorption layer 404 can be formed using a conductive material, a semiconductor material, or an insulating material. For the light absorption layer 404, a conductive material such as any element of Cr, Mo, Ni, Ti, Co, Cu, and Al; or an alloy material or a compound containing the element as its main component can be used. As the compound, a nitrogen compound, an oxygen compound, a carbon compound, a halogen compound, or the like can be used, and for example, aluminum nitride, tungsten nitride, tantalum nitride, or the like can be used. Alternatively, a semiconductor material such as silicon, germanium, silicon germanium, molybdenum oxide, tin oxide, bismuth oxide, vanadium oxide, nickel oxide, zinc oxide, gallium arsenide, gallium nitride, indium oxide, indium phosphide, indium nitride, cadmium sulfide, cadmium telluride, or strontium titanate can be used. Further alternatively, an organic resin material such as polyimide, acrylic, polyamide, polyimideamide, resist, or benzocyclobutene; or an insulating material such as siloxane or polysilazane can be used. Further, zinc sulfide, silicon nitride, mercury sulfide, aluminum chloride, or the like can be used. The light absorption layer 404 can be formed with a single layer structure or a stacked layer structure.

The light absorption layer 404 is formed by an evaporation method, a sputtering method, a CVD method, or the like. In the case where the light absorption layer 404 is formed using an insulating material, it can be formed by a coating method. Further, hydrogen or an inert gas (rare gas such as helium (He), argon (Ar), krypton (Kr), neon (Ne), or xenon (Xe)) may be added to the light absorption layer 404. When hydrogen or an inert gas is added to the light absorption layer 404, discharge of a gas from the light absorption layer 404 or evaporation of the light absorption layer 404 can be easily caused in subsequent laser beam irradiation.

The insulating layer 406 is formed using a material which can transmit a laser beam. For example, a light-transmitting inorganic insulating material or organic insulating material, or the like can be used. As the inorganic insulating material, silicon oxide, silicon nitride, silicon oxynitride, silicon nitride oxide, or the like can be used. As the organic insulating material, an organic resin such as polyimide, acrylic, polyamide, polyimide amide, benzocyclobutene, or an epoxy resin can be used. The insulating layer 406 can be formed by a sputtering method, a CVD method, a coating method, or the like using the above material with a single layer structure or a stacked layer structure.

The photomask 408 includes a light-transmitting region 410 which transmits the laser beam 414 and a light-blocking region 412 which blocks the laser beam 414, and the light-transmitting region 410 and the light-blocking region 412 form a desired pattern. For example, the photomask 408 is formed of a substrate obtained by forming a desired pattern using a light-blocking material on a surface of a light-transmitting substrate. It is to be noted that a material for forming the light-blocking region 412 needs to be a material favorable in light-blocking property and resistant to energy of the laser beam 114. For example, in the case of using an excimer laser beam, tungsten, molybdenum, or aluminum can be used.

As the laser beam 414, a laser beam having such energy that can be absorbed by the light absorption layer 404 may be appropriately selected. Typically, a laser beam of an ultraviolet region, a visible region, or an infrared region may be appropriately selected.

The description continues in the full USPTO document.